Nausea, vomiting, diarrhea, and loss of appetite may occur. Temporary hair loss may also occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.
People using this medication may have serious side effects. However, you have been prescribed this drug because your doctor has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk.
Tell your doctor right away if you have any serious side effects, including: joint pain/swelling, black stools, vomit that looks like coffee grounds, signs of kidney problems (such as change in the amount of urine, pain in the lower back/side).
Get medical help right away if you have any very serious side effects, including: symptoms of liver disease (such as nausea/vomiting that doesn't stop, stomach/abdominal pain, yellowing eyes/skin, dark urine).
This medication may decrease bone marrow function, an effect that may lead to a low number of blood cells such as red cells, white cells, and platelets. This effect can cause anemia, decrease your body's ability to fight an infection, or cause easy bruising/bleeding. Tell your doctor right away if you develop any of the following symptoms: unusual tiredness, pale skin, signs of infection (such as sore throat that doesn't go away, fever, chills), easy bruising/bleeding.
Mercaptopurine may rarely increase your risk of developing certain types of cancer (such as lymphoma, skin, cervical). This risk is higher in children/young adults being treated for certain bowel diseases (such as Crohn's disease, ulcerative colitis). Tell your doctor right away if you develop any of the following symptoms: swollen abdomen, swollen lymph nodes, night sweats, unexplained weight loss, unusual skin changes (such as new skin lesion or bump, or change in size or color of a mole), unusual vaginal bleeding/discharge.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.